Duplex deal: Is this owners analysis wrong

[Shawn Crawley]

I've been in talks with a owner who wants to sell his property off market. He wants to sell for $70,000. My real estate agent friend tells me the ARV is $60,000. When I discussed this with him he says on the open market he could get atleast $100,000 because his total rent for both sides is $1000 a month. I thought valuing a propery based on rents is what is used with large multi-families. Am I wrong about this?